Oligoclonal and polyclonal binding-pair member mixtures are valuable tools in the treatment of disease, especially infectious disease and cancer. Employing a composition containing a plurality of binding-pair members that bind to more than one epitope can increases the efficiency of respective compositions, and decrease the risk of epitope escape, for example. Such immunoglobulin mixtures furthermore enable the targeting of different pathogens or specific subfamilies or subspecies of a certain pathogen or a certain cell population, especially in circumstances where the generation of cross-reactive antibodies is not possible or not desirable.
Several strategies for the production of oligoclonal and polyclonal binding-pair members, such as antibody mixtures, exist. In its easiest form each single antibody is produced from a separate cell line, i.e. each antibody is produced from a single cell line in separate growth vessels, typically fermenters. Thereafter, the individual antibodies are mixed afterwards to form the oligoclonal or polyclonal antibody mixture. See panel A in FIG. 1. As is evident, this approach requires many resources and is therefore commercially unattractive.
In another approach, each antibody is still produced from a separate cell line, but the cell lines are mixed in one growth vessel, typically a fermenter. This approach has the shortcomings that it is essentially impossible to control the growth of different cell lines in one fermenter, thereby rendering production more or less to a gamble. These issues get even more complicated if more than two antibodies are produced, since some cell line might be able to out-grow others, thereby suppressing the production of some immunoglobulins of the mixture. See for example WO2008/145133. This approach is depicted in panel B in FIG. 1.
In yet another approach, two or more antibodies are produced in the same cell line, which a fortiori takes place in one growth vessel. The disadvantage of this approach hails from the heterodimeric nature of the immunoglobulins. The variable heavy chain of one antibody will not only pair with its “own”, designated variable light chain, but also undesirably with the variable light chain of the second (or any further, subsequent) antibody produced by the host cell. This situation gets even more complicated if more than two antibodies are produced by such host cell. The antibodies formed by incorrectly paired immunoglobulin chains may outnumber the number of correctly formed antibodies, and hence this approach is also nothing but an inadequate solution. See panel C in FIG. 1.
Finally, another approach uses “dummy”, common light chains (see U.S. Pat. No. 7,429,486). In this approach the specificity of the antibody comes from the variable heavy chain; and the light chain common to all antibodies produced in this system is merely a means to provide a full length immunoglobulin. However, since all antibodies need to be functionally active, the use of a common light chain goes along with a reduction of the types and properties of the immunoglobulins that can be produced. Furthermore, the production of the different heavy chain cannot be adequately controlled, leading to a more or less uncharacterized mixture of immunoglobulins. See panel D in FIG. 1.
Taken together, there is still no satisfactory way to efficiently produce a polyclonal or oligoclonal mixture of immunoglobulins. As will be evident, the methods disclosed in the present invention are not just applicable to immunoglobulins, but to all heteromeric multimeric proteins.